LM7 upgrades for rock crawler??

[tdkask]

New to the forum and LS engines. I have tried to read up but there is just so much that only makes sense after you know it, so please go easy on me if I'm asking questions that should seem obvious.

I'm helping my buddy with a rock crawler build, basically all custom frame and suspension with an old school Jeep body and grill, and after reading up we decided that LSX powertrain was the way to go. Wanting to stay in a budget for engine he jumped at the opportunity when he was able to get a '99 LM7 drop for $280 (no harness or computer). We will be buying a used factory harness and PCM and doing the wiring mods ourself, getting the PCM reprogrammed.

The question is this: Without spending a lot of cash, what are worthwhile upgrades to this engine? We'd consider dropping in a factory cam from a LS? motor, but don't know it's be worth the $50-$100 in parts. What would be the best (stock) cam that would be a direct bolt-in (springs and pushrods matched, of course)? Also, what throttle body would serve best? Would an injector upgrade be in order? While the engine is apart for inspection, would we benefit from swapping in 4.8 (flat) pistons? Is there anything to gain by "gasket matching" heads?

Basically I'm looking for the "formula" to get more out of this on the cheap, with a focus on torque as much as HP. Though HP is good for a large hill climb, it's the torque that pushes you over the rocks.

For now, we'd considered the following:
air intake (before TB) will just be a short large diameter tube and a K&N filter... no restrictions before TB.
The plan for the exhaust is to cut just behind FWD O2 sensors on stock exhaust and run same diameter, unrestricted, from there back.
All smog will be deleted.
Fan will be electric.
AC compressor will be retained, but not engaged (except as occasional air compressor for tires, etc).
Manual (SM465) trans
F-body oil pan (for rock clearance)

With this setup, based on what I've read, we expect to see around 315-ish HP. Is that about right? Is there a cam combo that, along with Camaro TB and performance PCM tune, will get us up to 400+ HP without sacrificing low end torque?

Also, does anyone here do/recommend performance tunes? We're considering garretttuning.com as the price seems good and it seems like it'd include whatever we need. Is there a better solution recommended?



Thanks for any advice and assistance.

[kerrige]

For your custom tuning needs look no further than Nelson performance. $300 and includes free retunes.
Hp/tq to the wheels of a stock 5.3 expect 200-225. With the basic mods you listed maybe 250-275.
400 to the wheels will require heads and cam or forced induction.
Best budget cam is prolly LS6 cam with hardened pushrods and yellow springs. $250-300ish and 40hp
or get a full out thunder racing cam kit for $600 and 75hp
Swapping to 4.8 pistons will be a great upgrade especially for downlow power.
78mm tb's are all the same, but some gains from a good p&P job.

[jansen]

Ls6 can doesn't have the bottom end grunt you need.

[bangbangskeetskeet]

If you have the heads off swap the flat top pistons in and get the heads milled.

Best bang for your buck for that type of performance IMO would be a maggie, and the other supporting mods like tuning and fuel system.

[kerrige]

Ls6 can doesn't have the bottom end grunt you need.

What? That is the baby cam of baby cams. Dyno sheet of a ls6 cam in a 5.7 with boltons. Note the torque curve.
http://ls1tech.com/forums/dynamomete...-firehawk.html

[bangbangskeetskeet]

What? That is the baby cam of baby cams. Dyno sheet of a ls6 cam in a 5.7 with boltons. Note the torque curve.
http://ls1tech.com/forums/dynamomete...-firehawk.html

He also added more parts than just the cam....just saying I would be willing to be that the majority of the gains seen there are NOT from the LS6 cam.

[jansen]

Everyone always complains about their lack of bottom end with this can in a truck. Also the engine in the link was a 5.7 and in a car, not a very good comparison for a rock crawler.

[blacstar]

and remember his budget, and for rock crawling he wants more torque. I would just drop in the lm7, tune, make the intake, and gears (4.56 or lower). im sure that chassis will be light enough!

[kerrige]

He also added more parts than just the cam....just saying I would be willing to be that the majority of the gains seen there are NOT from the LS6 cam.

Everyone always complains about their lack of bottom end with this can in a truck. Also the engine in the link was a 5.7 and in a car, not a very good comparison for a rock crawler.

We are talking torque curves here. The dyno doesn't lie when it comes to the actual curve and those boltons are very basic ones the OP suggested he would be using. The 5.7 is only very slightly different from the LM7 power wise. Also car vs truck doesn't change a torque curve on a dyno. The LS6 cam shows significant gains for the price including down low. You can't expect big gains down low no matter what the cam. He asked what stock cam would work and still receive a bump in performance. It will still be better than stock which is what he asked.

[jansen]

Also car vs truck doesn't change a torque curve on a dyno.

. It will if its got a car intake on it.